1. Field
The following description relates to a delta-sigma modulator. The following description further relates to a delta-sigma modulator having a differential output.
2. Description of Related Art
In general, a signal may be more easily processed in a digital form, rather than an analog form. For this reason, research has been continuously conducted relating to converting an analog signal into a digital signal. Once the analog signal is in digital form, it is represented in discrete form rather than a spectrum of continuous values, making the signal easier to process.
A process of converting the analog signal into the digital signal may also be referred to as an analog-to-digital conversion. An accuracy of the digital signal converted from the analog signal may be a significant aspect of the analog-to-digital conversion. Such an accuracy plays a significant role because if the digital representation of the analog signal is inaccurate, there may be large discrepancies and errors introduced into processing the signal as a result of the conversion.
A delta-sigma analog-to-digital converter (ADC) may oversample an analog input signal, convert the oversampled analog input signal into a one-bit digital bitstream through a delta-sigma modulation, and generate multi-bit digital data based on the one-bit digital bitstream.
In some ADC approaches, an analog signal is sampled with a sampling frequency and subsequently quantized using a multi-level quantizer to produce a digital signal. However, this process adds quantization error noise to the signal. In delta-sigma modulation, first, delta modulation is performed, so that the delta or change in a signal is coded instead of its absolute value. After the delta modulation, the signal becomes a stream of pulses. In delta-sigma module, the modulated stream is made even more accurate by passing the output throughout a 1-bit DAC and performing a sigma, or addition, operation to add the resulting analog signal to the input signal, and this reduces the error resulting from the delta-modulation.